Quick, the grid is down—what do you do?
If your procedures are like most, you rely on a combination of static restoration plans, emergency management system protocols, and operator experience and intuition. But today’s grid is increasingly complex and is subject to new vulnerabilities.
Physical security is a critical concern, especially in the wake of recent high-profile attacks against America’s electrical transmission infrastructure. These incidents paved the way for new physical security requirement recommendations from the North American Electric Reliability Corp., which should be adopted industry-wide to avoid disruptive events. But fully protecting the grid requires us to look at internal threats as well as external ones, and to put systems in place to reduce vulnerabilities at the operator level for utilities and power generation.
We must recognize that no system is 100% blackout proof. America’s aging infrastructure and our changing mix of energy creates significant system vulnerabilities that make bringing the grid back online more challenging and potentially more costly for utilities as well as their customers.
In the event of a blackout, grid operators rely on a limited number of “black-start units”— generators with a self-start capability, to jumpstart the grid. Once the black-start units are operational, grid operators then generate “cranking paths” from these generators to non-black-start units, which require external power sources to start up, to bring the rest of the grid online. These cranking paths are typically generated using static plans based on a set of assumptions about equipment availability, infrastructure integrity, and other variables that may or may not be valid for the specific emergency at hand. Experienced grid operators must make adjustments to these cranking paths based on their knowledge of the specific circumstances and their experience in handling outages and power overloads.
However, ongoing changes over the last decade have altered many of the assumptions underlying operator intuition and can make the grid more complex to bring back up after a blackout.
Alternative Fuels Add Uncertainty
The switch from coal-fired power plants to gas generation has introduced new vulnerabilities to the system as a whole. While natural gas brings many benefits, gas plants rely on pipelines to bring in fuel as it is burned. Unlike traditional coal plants, gas facilities typically do not have large volumes of fuel stored on site. A large-scale disaster that interrupts the power grid may also interrupt the gas supply to these power plants, leaving fewer resources for power plant operators to rely on to create cranking paths back to restoration.
Greater focus on renewable energy sources also introduces uncertainty, as it is difficult to predict how much power they can generate (if any) after a disaster strikes, making them unsuitable for restoration.
Many black-start plans utilized old, reliable coal plants that are now being retired. Combined, this means that grid operators have fewer options to rely on to restore the grid during a blackout.
Grid Complexity Creates Unpredictability
The increased complexity of the grid as a whole also makes it more difficult to adjust recommendations and generate new cranking paths on the fly. The increasing sophistication and automation of power distribution systems and the smart grid increase this unpredictability. Higher degrees of connectivity, reliance on more distant power sources, and a system that combines aging infrastructure with a hodgepodge of new technologies make it harder to predict the effects of decisions that a grid operator makes.
Technology Holds the Key
One way to speed a recovery effort is to take advantage of new technologies that enable real-time command and control over the grid. A good example can be found in the use of the Agora system by utilities in Spain and California. Agora is a system developed by Gridquant that takes advantage of a patented, deterministic load-flow solver that allows operators to visualize grid conditions in real time, even up to the point of voltage collapse. In the event of a blackout, it operates much like a GPS, providing dynamic, step-by-step guided solutions that are continuously recalculated in response to changing grid conditions and equipment availability.
Agora was originally created for Spanish utilities that lacked the ability to provide real-time, guided solutions to utility operators for avoiding and recovering from blackouts. Since its implementation in 2000, the Agora tool has become an integral piece of transmission operations at Endesa. Similarly, after the San Francisco blackout of 1998, Pacific Gas & Electric recognized it needed a solution to ensure it could restore customers as quickly and safely as possible. Agora provided the needed real-time, dynamic support for restoration.
In both of these instances, investments in analytical planning software like Agora replaced outdated or unreliable intuition with real-time information that helps operators respond to emerging conditions to prevent a blackout or rapidly restore the grid if a blackout occurs.
As we continue to add complexity and uncertainty to our power grids, we must also develop and implement effective new tools to help operators address these mounting concerns. The restoration plans of yesterday, based largely on experience and intuition, no longer make sense. By leveraging technology, operators can improve the resiliency of the grid and reduce the variables that prevent efficient restoration. ■
— Dr. Jason Black is a research leader in Battelle’s Energy Systems business and leads Battelle’s transmission modeling initiatives with Gridquant and the commercialization of Battelle’s demand-response management system.